Service providers (e.g., private companies or governmental organizations) utilize computer systems to perform routine tasks, such as billing/payment processes. Self-service scenarios can be convenient and provide cost savings not only for the provider, but also for the customer. For example, a customer can review invoice or bank accounts that are presented by a browser interpreting a page.
The following documents are useful:                U.S. Pat. No. 6,175,823,        U.S. Pat. No. 6,336,098, and        U.S. Pat. No. 6,324,525.        
For invoices with multiple items that either charge or deduct to/from the customer's bank account, there is a technical task to calculate balances and to communicate items to/from the customer with minimum load to the network.